Compositions comprising ratite oil or active fractions thereof and methods of using these composition as insect repellents

ABSTRACT

This invention provides compositions for repelling insects, particularly biting insects, such as mosquitoes, ticks, and biting flies comprising ratite oil, active fractions of ratite oil obtained by flash chromatography or compositions comprising mixtures of fatty acids found in ratite oil. Also provided are compositions for repelling insects comprising ratite oil, active fractions of ratite oil or compositions comprising mixtures of fatty acids found in ratite oil further comprising at least one additional insect repellent. Methods of repelling insects, particularly biting insects, are provided comprising topically applying ratite oil, active fractions of ratite oil, or compositions comprising mixtures of fatty acids found in ratite oil; or ratite oil, active fractions thereof, or compositions comprising fatty acids found in ratite oil and further comprising at least one additional insect repellent.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.08/914,429, filed Aug. 19, 1997, now abandoned, which is acontinuation-in-part of U.S. Ser. No. 08/876,268, filed Jun. 16, 1997,now U.S. Pat. No. 5,929,113, which is a continuation-in-part of U.S.Ser. No. 08/849,748, filed Jun. 12, 1997, now abandoned, which is theU.S. National Phase filing of PCT/US97/04101, filed Mar. 13, 1997, nowabandoned, which is a continuation-in-part of U.S. Ser. No. 08/746,894,filed Nov. 18, 1996, now U.S. Pat. No. 5,677,388, issued Oct. 14, 1997,which is a continuation-in-part of U.S. Ser. No. 08/616,708, filed Mar.15, 1996 now U.S. Pat. No. 5,626,882, issued May 6, 1997, thedisclosures of each of which are incorporated herein by reference intheir entirety.

TECHNICAL FIELD

This invention is in the field of topical insect repellents. Moreparticularly, effective, natural and safe biting fly repellentscomprising oil from ratites, which include rheas, emus, ostriches, kiwisand cassowaries, active fractions of ratite oil and compositionscomprising ratite oil or active fractions thereof and citronella orcitronella and saponin are provided. Composition comprising ratite oilor active fractions thereof and at least one other insect repellent arealso provided. In addition, compositions for repelling biting insectscomprising a mixture of fatty acids are provided. Methods for repellinginsects comprising applying such compositions are also provided.

BACKGROUND ART

This invention relates to a compositions and methods for repellinginsects, and more particularly to compositions and methods for repellingbiting insects such as mosquitoes and biting flies, for example,ceratopogonid flies, using a natural ingredient, oil from ratites, whichinclude rheas, emus, ostriches, kiwis and cassowaries, active fractionsof such oils and compositions comprising ratite oil or active fractionsthereof and at least one other insect repellent such as citronella orDEET, optionally, further comprising saponin. Also included arecompositions for repelling insects comprising a mixture of certain fattyacids and methods for repelling insects comprising application of suchcompositions comprising certain fatty acids.

Known natural oils that repel insects include rotundial (from the leavesof Vitex rotundifolia, Watanabe K et al. (1995) Biotech Biochem59(10):1979-1980); citronella oil (e.g. U.S. Pat. No. 5,346,922);eucalyptus oil (Watanabe et al. (1993) J. Agric. Food Chem.41:2164-2166); neem oil (Sharma V P et al. (1993) J. American MosquitoControl Association 9(3):359-360); and oil of Hedeoma pulgioides, oil ofanisum and oil of chrysanthemum (U.S. Pat. No. 5,208,209). Anothernatural oil that has repellent activity is saponin (Croda fromSapindus). Saponin has been shown to repel lice and also serves toimprove the spreading consistency of repellent compositions and reducegreasiness.

However, the compound most widely used as a topically-applied insectrepellent is N,N-diethyl-m-toluamide (DEET). When applied to children'sskin, DEET has been implicated in causing convulsions. DEET is alsoknown to react with certain plastics and synthetic rubber and cause skinirritation (Watanabe et al. (1993), supra). As a result of theseproblems and other side effects, New York State had banned productscomprised of 100% DEET.

The active fractions of the naturally-occurring insect repellents arealso largely unknown. Methods of resolving heterogeneous compounds intochemical species are well-known in the art. For example, silica gelflash chromatography provides for high speed resolution of organiccompounds (see, e.g., U.S. Pat. No. 4,293,422). After separation, theeluted fractions can be recovered and tested for the activity ofinterest.

Franz Bencsits, U.S. Pat. No. 5,589,181, has reported that certain C1 toC4 fatty acid alkyl esters and fatty alcohols preferably having 5 to 18carbon atoms have insect repellent activity. Bencsits discloses that theC1 to C4 fatty acid alkyl esters can be obtained from C5 to C9 fattyacids present in rape-seed oil, sunflower oil, peanut oil, peanutbutter, soy oil, safflower seed oil, cuphea oil, coconut oil, palmkernel oil, palm oil and fish oil. The fatty alcohols may be obtainedfrom paraffin and/or ethene. Bencsits further discloses that in order toslow down the evaporation of the active substances, the C1 to C4 fattyacid alkyl esters and/or the fatty alcohol, a carrier can be providedconsisting of natural or nature-identical vegetal and/or animal oils.Bencsits does not, however, teach or suggest the compositions of theinstant invention.

Accordingly, there remains a need for a natural, safe substance thatacts to repel insects, particularly biting insects, when topicallyapplied to the skin. The active fraction(s) of such a substance are alsoneeded as are effective compositions comprising ratite oil or activefractions thereof and compositions comprising ratite oil or activefractions thereof in combination with at least one other insectrepellent such as citronella, DEET or saponin. Compositions comprisingmixtures of fatty acids that effectively repel insects are also needed.

SUMMARY OF THE INVENTION

The present invention provides a method for repelling insects,particularly biting insects, comprising topically applying ratite oil,active fractions of ratite oil, or a composition comprising a mixture offatty acids to a subject. Methods for repelling insects, particularlybiting insects, comprising topically applying compositions comprisingratite oil, active fractions thereof or mixtures of fatty acids and atleast one other insect repellent such as citronella or DEET to the skinof a subject are also provided. The invention further providescompositions for repelling biting insects comprising active fractions ofratite oil or a mixture of fatty acids or compositions comprising ratiteoil, active fractions thereof or a mixture of fatty acids and at leastone other insect repellent such as citronella, DEET or saponin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the number of mosquitoes present on filter paper treatedwith water, sucrose or sucrose and diluted emu oil (sample 776) at 2.5minute intervals. The solid triangles show water-treated filter papercontrols. The open squares show sucrose-treated filter paper. The solidsquares show sucrose-treated paper overlaid with undiluted sample 776.The open triangles show sucrose-treated paper overlaid with a 50%dilution of sample 776. The open circles show sucrose-treated paperoverlaid with sample 776 diluted to 25%.

FIG. 2 shows the number of mosquitoes present on filter paper treatedwith water, sucrose, or sucrose and fractions of sample 776 at 5 minuteintervals. The solid squares show water-treated paper. The open squaresshow sucrose-treated paper overlaid. The solid triangles showsucrose-treated paper overlaid with a sample 776. The open trianglesshow sucrose-treated paper overlaid with fraction F1. The solid circlesshow sucrose-treated paper overlaid with fraction F2.

FIG. 3 shows the ¹H NMR spectrum of the F1 fraction of emu oil.

FIG. 4 shows the ¹H NMR spectrum of the F2 fraction of emu oil.

FIG. 5 shows the average number of mosquitoes biting test limbs per tenminute intervals.

MODES FOR CARRYING OUT THE INVENTION

Throughout this application, various publications, patents and patentapplications are referred to by an identifying citation. The disclosuresof these publications, patents and patent applications are herebyincorporated by reference into this application to more fully describethe state of the art to which this invention pertains.

The present invention provides methods of repelling insects,particularly biting insects, using oil from ratites, which includerheas, emus, ostriches, kiwis and cassowaries, and is a natural and safesubstance. The invention also includes methods of repelling insectscomprising applying active fractions of ratite oils. The presentinvention also provides compositions for repelling insects comprisingfatty acids that have a repellent effect. The invention also providesfor methods of repelling insects comprising applying such compositionscomprising mixtures of fatty acids topically. In a preferred embodiment,pure ratite oil is applied to the skin. In another preferred embodiment,diluted ratite oil is topically applied. In yet another preferredembodiment, an active fraction of ratite oil is applied to the skin. Ina further preferred embodiment, a composition comprising ratite oil oran active fraction thereof and at least one other insect repellent isapplied to the skin. Suitable insect repellents that can be combinedwith ratite oil or an active fraction thereof include, but are notlimited to, N,N-diethyl-m-toluamide (DEET) citronella oil, rotundialoil, eucalyptus oil, neem oil, oil of Hedeoma pulgioides, oil of anisum,oil of chrysanthemum and saponin.

The present invention further provides compositions for repelling bitinginsects comprising ratite oil, active fractions of ratite oil or amixture of fatty acids. Also included are compositions comprising ratiteoil, an active fraction thereof or a mixture of fatty acids and at leastone other insect repellent. Suitable insect repellents that can becombined with ratite oil, an active fraction thereof or a compositioncomprising a mixture of fatty acids include, but are not limited to,N,N-diethyl-m-toluamide (DEET), citronella oil, rotundial oil,eucalyptus oil, neem oil, oil of Hedeoma pulgioides, oil of anisum, oilof chrysanthemum and saponin.

Compositions comprising ratite oil, an active fraction thereof or amixture of fatty acids and at least one other insect repellent werefound to exhibit surprisingly unexpected synergistic results. Therepellent activity of these compositions was much greater than eitherratite oil, active fractions of ratite oil, a mixture of fatty acids orthe other insect repellent alone. This synergistic effect was alsoobserved with diluted preparations of ratite oil and another insectrepellent.

The following examples are presented as a further guide to thepractitioner of ordinary skill in the art, and are not to be construedas limiting the invention in any way.

EXAMPLES Example 1 The Effect of Emu Oil on Frequency of Mosquito Landsand Bites

To determine if emu oil was an effective mosquito repellent, pure emuoil (Zoogen, Inc., Davis, Calif.) was applied to one hand of avolunteer. The other hand was left untreated. Each hand was placed in anylon mesh cage containing mosquitoes (Aedes aegypti) and the number ofmosquitoes which landed and/or bit in 30 seconds was recorded. Theexperiment was performed in duplicate. Results of the experiments wereaveraged and are summarized in Table 1.

TABLE 1 emu-oil treated hand untreated hand (lands/bites) (lands/bites)Test 1 0/0 11/11 Test 2 1/0 26/26

These results demonstrate that topically applied emu oil is an effectivemosquito repellent. It greatly reduces the number of mosquitoes whichland, and completely eliminates biting.

Example 2 The Effectiveness of Emu Oil as a Mosquito Repellent Over Time

To determine how long topically applied emu oil maintains efficacy as amosquito repellent, the treated hand was exposed to a cage of mosquitoesat 15, 30 and 60 minutes after application. The number of lands andbites were compared at each time point with the untreated hand. Resultsfrom duplicate experiments were averaged and are presented in Table 2.

TABLE 2 Number of lands on emu- Number of lands on Time afterapplication oil treated hand untreated hand 15 4 18 30 2 12 60 10 12

These results show that emu oil remains an effective mosquito repellentfor at least 30 minutes.

Example 3 The Effectiveness of Diluted Emu Oil

To determine the effectiveness of diluted emu oil, the emu oil wasdiluted with ethyl acetate to a fixed percentage, applied to one handand inserted into a mosquito cage. The number of lands were recorded.The experiments were performed in duplicate at each dilution level.Results are shown in Table 3.

TABLE 3 Number of lands Number of lands Average Number Percent emu oilExp't 1 Exp't 2 of lands 0 10 9 9.5 0.50 10 10 10 1.0 5 5 5 5.0 6 4 510.0 4 5 4.5 25.0 2 1 1.5 50.0 1 1 1 75.0 1 1 1 100.0 0 0 0

These results demonstrate that dilute amounts of emu oil effectivelyrepel mosquitoes. At a dilution as low as 1%, emu oil reduces byone-half the number of mosquitoes which land. At 25% emu oil, the numberof mosquito lands drops to one-tenth of lands on an untreated hand.Thus, emu oil is an effective insect repellent at a concentration of 1%or higher.

Example 4 Fractionation of Emu Oil and the Effectiveness of theFractions

An 850 mg sample (776) of emu oil was steam-distilled and fractionatedusing silica flash chromatography (Baker silica gel, 40 μm), essentiallyas described in Still et al. (1978) J. Organic Chem. 43:2923. Two majorcomponents of the sample were eluted from the column with 100% hexaneand 25% ethyl acetate/hexane. Fractions were analyzed by thin layerchromatography (TLC) on silica plates developed with 50% hexane/ethylacetate. Components on the TLC plates were observed by exposing theplates to UV light (indicating UV chromophores) and spraying plates withvanillin/sulfuric acid (indicating the presence of higher alcohols,sterols, phenols or essential oils). 430 mg of a clear oil, termed F2,was found to be UV active and reactive to vanillin/sulfuric acid. Thesecond component, 380 mg of a pale yellow oil termed F1, was not UVactive and did not stain with vanillin. F1 and F2 fractions wereanalyzed by ¹H NMR (300 MHz, CDCl₃) as shown in FIGS. 3 and 4.

A mosquito repellent bioassay was performed by treating wedges of filterpaper with sucrose overlaid with either an aliquot of the crude sample776, F1 or F2. Filter paper treated with water or sucrose served ascontrols. Samples of F1 and F2 were tested at full-strength or dilutedwith corn oil to 50% or 25% of full-strength. At regular time intervals,the number of mosquitoes which landed and fed on the wedges of filterpaper was recorded. Results are shown in FIGS. 1 and 2.

As shown in FIG. 1, even diluted to 25% of full-strength, the crudesample (776) greatly reduces the number of mosquitoes landing on thesucrose paper. In addition, FIG. 2 shows that both the F1 and F2fractions of sample 776 at full-strength and diluted to 50% or 25% offull-strength were effective in repelling mosquitoes when compared tothe sucrose-treated control.

Example 5 The Effect of Emu Oil as a Tick Repellent

To determine if emu oil was an effective tick repellent, a testsubject's hands were treated with emu oil while the fingers of the handwere left untreated. As a positive control, Ultrathon (3M, Minneapolis,Minn.) was applied to the hand and the fingers were left untreated. Anuntreated hand was used as a negative control. Unfed nymphal WesternBlack-legged ticks were placed on the fingers of the hands and observedas they climbed toward the treated or untreated skin of the hand. Tickscrossing onto the treated skin were scored as “crossing.” Those notcrossing were scored as “repelled.” Ticks were removed after a singlescore was recorded. Repellency is calculated as the proportion of alltrials in which a tick is repelled. For example, 8 repels in 10 trialsprovides a repellency of 80%. In this study, each subject tested a tickat 15 minute intervals for 2 hours and 15 minutes. The results are shownbelow:

Negative control - untreated skin -  0% repellency Positive controlUltrathon (3M) - 70% repellency Emu oil - 40% repellency

There was no indication that the repellency declined over the two hourtest period.

Example 6 The Effect of a Composition of Emu Oil and Citronella onFrequency of Mosquito Bites

To determine if citronella would enhance the mosquito repelling effectof emu oil, the repellent activity of emu oil alone and a compositioncomprising emu oil and citronella (30 drops of 100% oil of citronella/25mL of pure emu oil) were compared to a positive control, Ultrathon® (3M,Minneapolis, Minn., approximately 31% DEET). Oil of citronella,Cymbopagon nardus, was obtained from Aura Cacia, Weaverville, Calif.

Testing was conducted in the Florida Keys, namely Big Pine Key andLittle Pine Key. During testing, the air temperature was 24-26° C., withclear skies and slight wind. Aedes taeniorhynchus accounted for >99% ofmosquitoes that approached or attacked subjects.

In the first study, three subjects applied pure emu oil, one subjectapplied Ultrathon, and two subjects served as negative controls. In thesecond study, oil of citronella was added to the emu oil. Three subjectsapplied the composition comprising emu oil and citronella, two subjectsapplied Ultrathon, and two subjects served as negative controls. Six ofthe participants were employees of the Monroe County, Fla., MosquitoControl Service. Treatments were evenly divided among leg and armsurfaces. The surface areas of treated surfaces were calculated for eachsubject in advance of the application. The test materials were appliedat dosage rate of approximately 3 mL/650 square centimeters of surfacearea.

Test subjects counted and recorded bites in a series of 10 minuteperiods. Counts were recorded on data sheets. In the first study, thetesting period was two hours, with 12 consecutive 10 minute recordingperiods. In the second study, the test was interrupted during two briefwindy periods by the need to move to more productive locales (i.e.,places with higher biting rates) within the test sites. As a result, thetotal testing period including the interruption was two hours andtwenty-five minutes.

Ambient biting rates were measured throughout the study by the subjectswith untreated control limbs. The average ambient biting rates weresufficient for testing in both studies and ranged between 17 and 70bites per 10 minute interval (mean=38.5; see FIG. 5).

Both emu oil and the positive control, Ultrathon, repelled mosquitoesover the test periods. A composition comprising emu oil and oil ofcitronella was particularly effective as a repellent (see FIG. 5). Therepellent properties of emu oil alone reduced the number of bites to anaverage of 5.7 bites per ten minutes. The composition comprising emu oiland citronella approximated the positive control, Ultrathon, with 0.8bites per ten minutes for the emu oil/citronella composition compared to0.2 bites per ten minutes for Ultrathon. Over the testing period, emuoil, a composition comprising emu oil and citronella and Ultrathonsubstantially reduced biting rates from Aedes taeniorhynchus. Acomposition comprising emu oil and citronella was much more effectivethan emu oil alone and offers protection comparable to that offered bymosquito repellents registered by the U.S. Environmental ProtectionAgency (EPA). No pattern of diminishing repellency over time wasobserved for emu oil and citronella.

Example 7 The Effect of a Composition of Emu Oil, Citronella and Saponinon the Biting Frequency of Ceratopogonid Biting Flies

To determine the efficacy of a composition comprising emu oil,citronella and saponin as a biting insect repellent, eight (8) humansubjects took part in an experiment wherein three (3) subjects weretreated with emu oil alone or emu oil with citronella and saponin. Threeother subjects served as the negative controls while two subjects weretreated with two commercially available insect repellents, Ultrathon™, aDEET-based repellent, and Treo™, a plant-based repellent. Testing wasconducted at three sites: a) on Big Pine Key, Fla.; b) at FairchildTropical Gardens, Miami, Fla.; and c) Hopkins Village, Belize, CentralAmerica. Temperatures ranged from 21-24° C., the sky was clear and thewinds were slight during each testing period.

Two preparations of emu oil were prepared for testing: a) 100% emu oilalone; and b) 20 mL emu oil plus 30 drops of oil of citronella and 2 mLsaponin (Croda, from Sapindus).

The two commercially available repellents used as comparative controlswere: a) Ultrathon™ (3M®, Minneapolis, Minn., a United StatesEnvironmental Protection Agency (EPA)-registered DEET-based product,approximately 32% DEET); and b) Treo™ (Primavera Laboratories, Inc.®,SPF 15 lotion with 0.05% citronella).

The negative control was untreated skin.

The test materials were applied either to the lower arm or lower legskin of the study subjects. The areas of treated skin surfaces werecalculated for each subject in advance of the application. Applicationsof the test materials, except Ultrathon, were made at a dosage of 3.0mL/650 cm², a dosage comparable to that used in studies of herbalrepellents for EPA registration. Ultrathon was applied at themanufacturer's recommended dosage of 1 mL/650 cm².

Each test subject recorded the number of bites received by ceratopogonidbiting flies on treated or control surfaces during sequential samplingperiods that began every 10 minutes, the overall test duration beingapproximately 1 hour. The EPA recognizes 1 hour as the requiredprotection duration for claims of repellency to small biting flies. Theresults are shown in Table 4 below.

TABLE 4 NUMBER MEAN NUMBER OF OF 10 NUMBER INSECT BITES: FORMULA MINUTEOF INSECT STANDARD TESTED SAMPLES BITES DEVIATION Control 36 5.61 4.07emu oil (100%) 12 0.67 1.11 emu oil + citronella 36 0.19 0.46 andsaponin Treo 12 2.75 3.49 Ultrathon 12 0 0

Biting rates were much lower on each of the test materials than with thecontrol. Biting rates with emu oil and with the emu oil, citronella andsaponin composition were much lower than with the control and lower thanthe EPA-registered herbal repellent, Treo. The emu oil, citronella andsaponin composition prevented biting altogether in many of the samplingperiods, with confirmed bites (a bite followed by another bite within 30minutes) recorded only on subject 1 in the first sampling period andsubject 3 in the third sampling period. Thus, emu oil has a pronouncedsynergistic effect when combined with a herbal repellent, such ascitronella.

Example 8 The Synergistic Repellent Effects of Emu Oil

A preparation of emu oil was prepared wherein the emu oil was diluted toa final concentration of 0.02% with ethanol. OFF! Skintastic™ (S. C.Johnson) was diluted with ethanol to a final concentration of 0.01%. A1:1 solution (by volume) of the diluted OFF! and the diluted emu oil wasprepared. A 1:1:1 solution consisting of 10 mL of the diluted 0.01%OFF!, 10 mL of the diluted 0.02% emu oil, and 10 mL of ethanol wasprepared.

In order to determine whether emu oil has an additive and/or asynergistic effect in combination with other insect repellents, thesepreparations were tested alone and in combination. Each preparation wasapplied to the hand of a volunteer and exposed to a population of Aedesaegypti mosquitoes for 20 seconds. The test was repeated three times foreach preparation. Positive control preparations were either 100% emu oilor 100% OFF!. Negative controls were untreated skin. The results of thistesting are shown in Table 5 below.

TABLE 5 NUMBER OF INSECT BITES PER TREATMENT 1:1:1 MIX of 0.02% 1:1 MIXof 0.02% emu oil, 0.01% 0.02% 0.01% emu oil and 0.01% OFF! and 100% 100%Untreated EMU OIL OFF! OFF! ethanol EMU OIL OFF! Control 4 5 1 0 0 0 5 45 2 0 0 0 5 3 5 1 3 0 0 4 mean 3.67 mean 5.00 mean 1.33 mean 1.00 mean0.00 mean 0.00 mean 4.67

These results show that diluted emu oil had both an additive and asynergistic repellency effect in combination with other dilutedrepellents, in this case a DEET-based repellent.

Example 9

The NMR spectra of the active fractions of emu oil characterized inExample 4 above were found to correspond to spectra of fatty acids.Compositions comprising various percentages of certain fatty acids knownto be present in emu oil were prepared and tested for repellentactivity. Table 6 below shows the chemical composition of one suchcomposition and comparative information vis-à-vis corn oil, which hasbeen previously shown to be non-repellent, and soybean oil, which is acomponent of an insect repellent recently introduced to the market asBiteBlocker™ (Consep, Inc., Bend, Oreg.). The percentages of fatty acidsin corn and soybean oil listed in Table 6 are from deMan, John M,PRINCIPLES OF FOOD CHEMISTRY (Avi Publishing Co., 1980). The percentagesof fatty acids in emu oil were obtained from FASTRAX Ratites, Inc.,Santa Ynez, Calif. and were published in WO 92/08470 (Ghosh et al.)which reports the anti-inflammatory activity of emu oil.

TABLE 6 Percent in Percent in Pure Percent in Commercial Emu OilReported Percent in Corn Percent in Fatty Acid Mgs in Mixture MixtureGrade Emu Oil in WO 92/08470 Oil Soybean Oil Myristic Acid 20 0.9 0.50.32 — Trace (14:0) Arachidonic Acid 4.2 0.2 — 0.2 — — (20:4) PalmiticAcid 625 28.7 23 21.3 13 11 (16:0) Stearic Acid 222 10.2 10 7.8 4 4(18:0) Linolenic Acid 12.2 0.56 0.7 0.4 — 9 (18:3) Palmitoleic Acid 833.8 — 5.6 — — (16:1) Oleic Acid 1008 46.4 45 54.5 29 25 (18:1) LinoleicAcid 200.3 9.2 10 7.2 54 51 (18:2)

Testing was conducted as in previous experiments reported in theforegoing examples. Tests were conducted in the outdoors in a wildlifearea in New Mexico in which the predominant species of mosquito is Aedesvexans, an aggressive biting insect. Tests were performed in the summermonths in the early afternoon (1430-1630 hours, Test 1) and in the lateafternoon/early evening (1515-1915 hours, Test 2) near a stream at anelevation of approximately 2500 meters. In two separate tests, foursubjects in total applied approximately 2.5 mL of the fatty acidcomposition shown in Table 6 to one lower arm. The other lower arm ofeach subject was untreated and served as a control.

Test 1

In Test 1, three subjects were exposed for a period of two hours.Ambient biting was estimated at three (3) bites per minute on eachuntreated lower arm. No bites were received by any of the test subjectson the treated arm surfaces over the two hour test period.

Test 2

In Test 2, one subject was exposed for a period of four hours. Theambient biting rate per lower arm was measured in each of twenty-four(24) ten (10) minute periods. The ambient biting rate average 0.5 bitesper minute and ranged from 0 to 1.5 bites per minute. The test subjectreceived one bite on the treated lower arm surface at approximately 225minutes after application of the composition. In contrast, the testsubject received a total of 116 bites on the untreated control lower armsurface during the 240 minute test period.

Thus, these results demonstrate that compositions comprising mixtures offatty acids present in ratite oil are effective as insect repellents.The mixtures of free fatty acids comprise about 0.32% to 0.9% myristicacid, about 0.2% arachidonic acid, about 21.3% to 28.7% palmitic acid,about 7.8% to 10.2% stearic acid, about 0.4% to 0.56% linolenic acid,about 3.8% to 5.6% palmitoleic acid, about 46.4% to 54.5% oleic acid,and about 7.2% to 9.2% linoleic acid by weight.

Having now fully described this invention, it will be appreciated bythose skilled in the art that the same can be performed within a widerange of equivalent parameters, concentrations and conditions withoutdeparting from the spirit and scope of the invention and without undueexperimentation. While this invention has been described in connectionwith specific embodiments thereof, it will be understood that it iscapable of further modifications. This application is intended to coverany variations, uses, or adaptations of the inventions following, ingeneral, the principles of the invention and including such departuresfrom the present disclosure as come within known or customary practicewithin the art to which the invention pertains and as may be applied tothe essential features hereinbefore set forth as follows the scope ofthe appended claims.

What is claimed is:
 1. A composition capable of repelling insectscomprising a mixture of free fatty acids isolatable from emu oil and atleast one additional insect repellent, wherein the mixture of fattyacids comprises about 0.32% to 0.9% myristic acid, about 0.2%arachidonic acid, about 21.3 % to 28.7% palmitic acid, about 7.8% to10.2% stearic acid, about 0.4% to 0.56% linolenic acid, about 3.8% to5.6% palmitoleic acid, about 46.4% to 54.5% oleic acid and about 7.2%,to 9.2% linoleic acid by weight.
 2. The composition of claim 1, whereinthe additional insect repellent is a natural oil.
 3. The composition ofclaim 1, wherein the additional insect repellent is selected from thegroup consisting of rotundial, eucalyptus oil, neem oil, oil of Hedeomapulgioides, oil of anisum and oil of chrysanthemum.
 4. The compositionof claim 1, wherein the additional insect repellent is selected from thegroup consisting of N,N-diethyl-m-toluamide (DEET), citronella andsaponin.
 5. The composition of claim 1, wherein the mixture of fattyacids comprises 0.9% myristic acid, 0.2% arachidonic acid, 28.7%palmitic acid, 10.2% stearic acid, 0.56% linolenic acid, 3.8%palmitoleic acid, 46.4% oleic acid and 9.2% linoleic acid by weight. 6.The composition of claim 1, wherein the fatty acids are isolated fromemu oil.
 7. The composition of claim 1, further comprising a carrier. 8.A method of repelling insects comprising topically applying acomposition comprising a mixture of free fatty acids isolatable from emuoil, wherein the mixture of fatty acids comprises about 0.32% to 0.9%myristic acid, about 0.2% arachidonic acid, about 21.3% to 28.7%palmitic acid, about 7.8% to 10.2% stearic acid, about 0.4% to 0.56%linolenic acid, about 3.8% to 5.6% palmitoleic acid, about 46.4% to54.5% oleic acid and about 7.2% to 9.2% linoleic acid by weight.
 9. Themethod of claim 8 wherein the composition further comprises at least oneadditional insect repellent.
 10. The method of claim 9 wherein theadditional insect repellent is selected from the group consisting ofN,N-diethyl-m-toluamide (DEET), citronella and saponin.
 11. The methodof claim 9, wherein the additional insect repellent is a natural oil.12. The method of claim 11, wherein the natural oil is selected from thegroup consisting of rotundial, eucalyptus oil, neem oil, oil of Hedeomapulgioides, oil of anisum and oil of chrysanthemum.
 13. The method ofclaim 8, wherein the mixture of fatty acids comprises 0.9% myristicacid, 0.2% arachidonic acid, 28.7% palmitic acid, 10.2% stearic acid,0.56% linolenic acid, 3.8% palmitoleic acid, 46.4% oleic acid and 9.2%linoleic acid by weight.
 14. The method of claim 8, wherein the fattyacids are isolated from emu oil.
 15. The method of claim 8, wherein thecomposition comprises a carrier.